Whilst on passage from Naxos Greece to Didim Turkey, the following wind died to such a level that I had to start my Yanmar engine. I smoothly set 1700 rpm which is my normal maximum other than when doing the monthly turbo clean as recommended by Amel. About half an hour later there was a thumping sound  which at first I thought was a rope getting wrapped around the prop. But the engine did not stall, so unlikely. I dived over the side and had a look. No rope, net etc and no marks on the blades.

The Vetus coupling on my boat is somewhat obscured by by the wooden plinth that sits on the top of the C-Drive support frame. The plinth supports the water tank that feeds fresh water to my toilets. Looking at the coupling closely, it was apparent that all four bolts that hold the two halves of the casing together and to the drive flange on the output of the gearbox, had sheared. The thumping sound was the rubber blocks jumping out of their recesses in the casing. On the Yanmar installation these bolts cannot be replaced without moving the entire engine aft and sliding the coupling away from the C-Drive, so an at sea repair was out of the question. I am told that the Volvo installation is easier, but I never had to do this on my previous boat so I don't know for sure. Fortunately the wind freshened late in the day and I diverted to Leros and managed to sail into the anchorage during the night. Two days later I was towed into Leros marina, where I still am eleven days later.

Not having good enough tools or manpower to move the engine myself, I made use of the marina mechanics. At the same time I read with concern the dreadful experiences of Craig and Eric when they tried to remove the coupling from the C-Drive input shaft. My mechanics experience was no better. After working on the problem for two days they had succeeded in moving the shafts apart by no more than 5mm. They said that they would now have to remove the entire engine to gain enough access to get a strong enough puller on the job to free the Vetus from the C-Drive. All this at €50/hour for the labour and €60 per day for the marina. I suggested they might remove the gearbox from the engine to create enough space, which they did. Using a heavy duty puller and a 4 foot lever arm on the compression bolt spanner, the 'Bloody Vetus as Eric named it' finally came off.

Examining the coupling, the casings looked OK and the rubber blocks were in not bad shape for an age of 15 years according to the mechanics. The bolts did not all fail at once, and probably failed due to working loose or stretching over time. Despite the fact that maybe three bolts were broken before the final breakdown, there was no noticeable additional vibration in the transmission even at 3000 rpm that I had used when clearing the turbo two weeks earlier. Clearly these bolts need to be examined and checked for tightness on a regular basis.

As the cost of a new coupling was only €297 plus tax and shipping from Amel, I decided to replace the entire unit for peace of mind. We would also not have to modify the shaft ourselves to fit the C-Drive. Maud did a super job with FedEx as far as Athens, but the local courier took far too long to get the part to Leros. Unfortunately Maud forgot to include the 4 bolts and nuts, and these are now on the way courtesy of Amel. The Vetus agent in Greece has no stock! Maybe we could find similar bolts in a garage for example, but the quality would be uncertain and this is too crucial an item to risk your boat for.

So why is the coupling to difficult to remove? Like Eric found, the modified shaft is simply machined to too tight a fit. There is no way the new coupling will slide on the C-Drive shaft as it comes even though the C-Drive shaft is in good condition. It would need a press to install it. It's a keyed fitting and not an interference fit so it should be a push fit. Like Eric, I have spent considerable time reducing the C-Drive shaft diameter with wet and dry until the new coupling is a snug hand fit. Assembled with Corrosion Block grease, next time it should be easy to remove.

It's the same story with the outhaul capstan drive shaft. It's made too tight. If you rub it down till it slides in easily, you will not end up breaking your gearbox trying to remove it. The same again for my bowthruster tube to drive motor housing. It used to be a devil to separate. Having opened up the motor recess slightly with a Dremel and an abrasive wheel, it is no longer a problem. Whilst I have every confidence in Amel's sub contractors following Amel's design exactly, the fact is in the corrosive real world we operate in, the tolerances need to be made greater if we are to avoid going through nightmare maintenance issues such as these.

Finally, I should point out that unbelievably when you buy a Vetus coupling from Vetus, the bolts that hold the dammed thing together are NOT included! You will need to order a SET64 kit separately if you have a 4" gearbox flange. A SET65 if you have a 5" one. Amel, being a good company DO include these bolts when you buy from them, but it may be worthwhile reminding them at order time to make sure they include them in the box.

To anyone contemplating removing their Vetus coupling from the C-Drive, be prepared for a difficult time.

Regards and good luck.

Ian Shepherd SM2K 414 Crusader Leros Greece

Those coupling bolts need checking on a regular basis.

Hello,

we are currently stuck n Rockland, ME after hitting a lobster pot and fracturing our Vetus Coupling.  In addition to replacing the rubber bushings (Vetus kit #K018), I also need to replace the broken aluminum hub assembly (two pieces) and possibly new 8 cm bolts.

Does anyone have Vetus part#’s and possibly a US Supplier to FedEx my order?

many thanks to this great, supportive group.
--
Kevin & Kristen Schmit
KIANA
SM #362

Guys,

thank you all for the support and information.  Amel is on vaca until the end of the month.  

Bill has given me some drawings of the coupling to bring to a machine shop for fabrication.  

Attached is a picture showing 3 of the 4 broken studs on shaft flange.

are these studs machine threaded into the flange?


--
Kevin & Kristen Schmit
KIANA
SM #362

Kevin and Kristen, 

Kevin, 

Doug,

Thank you.  I just sent you personal email.
This takes care of the Vetus coupling.  

Ill check with a Vetus distributor to see if they can provide a new shaft flange assembly.  Let me know if anyone else has had to replace this and possibly a part#.

regards,
--
Kevin & Kristen Schmit
KIANA
SM #362

Mike,

I’ll swing by on the dinghy in the morning.
we’re on a mooring in front of Rockland Marine.
--
Kevin & Kristen Schmit
KIANA
SM #362

Kevin,
You might make a quick call and email to amel.caraibes@...